The same principle holds true for insider buying and selling. You never really know why the seller sells. There are plenty of reasons to pare or exit a position without turning completely negative on a stock. Heck, just consider asset allocation and diversification — they’re core principals of portfolio management, and they often force you to sell your winners.

Besides, as Buffett has said, the best reason to sell is because you’ve found better opportunities elsewhere.

Throw in the fact that Oracle of Omaha is putting a couple potential successors through their paces, and it’s likely he’s giving new portfolio managers Todd Combs and Ted Weschler more room to run with their best ideas.

Still, those sells are at least taking a quick look at:

Berkshire pared its holdings in Dow components Johnson & Johnson (NYSE:JNJ) and Procter & Gamble (NYSE:PG) in the second quarter, a new regulatory filing shows, but Buffett pretty much telegraphed the moves.

P&G, which makes everything from Tide detergent to Pampers diapers to Gillette razors, has seen its stock languish in 2012, as seemingly nothing has gone right. The company had to cut its sales and earnings outlooks twice in three months, as sluggish global growth, especially in developed markets, weighed on business. And Buffett noted a few months back that P&G can’t raise prices in a world where shoppers are opting for cheaper generic and store-brand products.

J&J, meanwhile, was hammered by a billion-dollar fine over marketing practices for one of its headline drugs, as well as recalls on some key products. Buffett has praised the company — but also said that it’s made too many mistakes lately.

And as for dumpingIntel (NASDAQ:INTC)? It was a small stake, held for less than a year — and Buffett never has hidden that fact that he doesn’t really do tech.

More interesting are Berkshire’s new and bigger positions in the energy sector. True, these are smaller stakes, so they’re most likely the doings of Combs and Weschler. But this is still Buffett’s shop, and the investments would have to fit his worldview if either guy has any hope of succeeding him.

Berkshire initiated a position in National Oilwell Varco (NYSE:NOV), holding more than 2.8 million shares in the oilfield equipment maker at the end of June. What does Berkshire see in the stock?

Well, for one thing, it looks like a bargain. National Oilwell trades at discounts to its own five-year average on both a trailing and forward earnings basis. Furthermore, its stock is rising, but not nearly fast enough to reflect its growth prospects, suggesting it’s still cheap. Additionally, it trades at similar multiples to the S&P 500, but has much stronger prospective earnings growth.

Operating margins of 20% and a strong balance sheet — with more cash than debt — only add to its appeal. And that’s despite a slew of deal-making in the past quarter. NOV, quite simply, looks like a quality stock at an attractive price.

The same characteristics can be seen in oil refiner Phillips 66 (NYSE:PSX). Either Weschler or Combs added to Berkshire’s position, which it initially received in a spin-off from ConocoPhillips (NYSE:COP).

PSX is the largest independent refiner by market cap, and it trades at steep discounts to the broader market and peers on both a trailing and forward earnings basis. More important, it has a strong balance sheet and generates ample cash, which it can then return to shareholders through dividends and buybacks. It’s a very Buffett-like buy.

Lastly, thematically, these energy plays fit with Buffett’s bullishness on the economy and America over the long haul. After all, energy is about as strategically cyclical as you can get.

Investors might want to take a closer look at NOV and PSX for their own portfolios. What Berkshire is buying is always more interesting than what it’s selling, and Buffett’s track record speaks for itself.

As of this writing, Dan Burrows did not hold a position in any of the aforementioned securities.